JP6824618B2 - Wide-angle lens - Google Patents

Description

The present invention relates to a wide-angle lens having a configuration of 5 elements in 4 groups.

The imaging lens includes a first lens, a second lens, a third lens, an aperture, a fourth lens, and a fifth lens arranged in order from the object side to the image side, and the fourth lens and the fifth lens are A wide-angle lens having a 4-group, 5-element configuration configured as a junction lens has been proposed (see Patent Document 1). In the wide-angle lens described in Patent Document 1, for the fourth lens and the fifth lens, a lens surface on the image side formed of a concave curved surface of the fourth lens and a lens surface on an object side formed of a convex curved surface of the fifth lens are used. A bonded lens is used, and a configuration that reduces chromatic aberration of magnification and the like is adopted.

JP-A-2015-45803

In the wide-angle lens described in Patent Document 1, the effective focal length of the entire lens system is 1 mm, and the central radius of curvature of the junction surface (9th surface) of the junction lens is 0.4327 mm. Therefore, since the curvature of the lens surface on the image side formed of the concave curved surface of the fourth lens and the lens surface on the object side formed of the convex curved surface of the fifth lens is large, the manufacturing process and the joining process of the lens alone can be stably performed. There is a problem that the load on the process is large, such as difficulty.

In view of the above problems, an object of the present invention is to provide a wide-angle lens capable of reducing aberrations without increasing the load on the process.

In order to solve the above problems, the wide-angle lens of the present invention is composed of the first lens, the second lens, the third lens, the aperture, the fourth lens, and the fifth lens arranged in order from the object side to the image side. The first lens is a negative meniscus lens having a convex surface facing the object side and a concave surface facing the image side, and the second lens is a negative lens having a concave surface facing the image side and is on the object side. At least one of the lens surface and the lens surface on the image side is an aspherical surface, and the third lens is a positive meniscus lens having a concave surface facing the object side and a convex surface facing the image side, and the lens surface on the object side and the lens surface on the image side. At least one of the lens surfaces on the image side is an aspherical surface, the fourth lens is a negative meniscus lens or a biconcave lens with a concave surface facing the image side, and the fifth lens is a biconvex lens. The four lenses and the fifth lens are plastic lenses, and constitute a bonded lens in which the lens surface on the image side of the fourth lens and the lens surface on the object side of the fifth lens are joined.
When the refractive index of the fourth lens is n4, the refractive index n4 has the following relationship n4 ≧ 1.632 ... Conditional expression (1)
The filling,
When the radius of curvature of the center of the junction surface of the junction lens is R45 and the effective focal length of the entire lens system is f0, the radius of curvature R45 and the effective focal length f0 have the following relationship 0.5 << R45 / f0 | <0.8 ... Conditional expression (2)
The filling,
When the Abbe number of the fourth lens is ν4, the Abbe number ν4 has the following relationship ν4 ≦ 24 ... Conditional expression (3)
It is characterized by satisfying.

In the wide-angle lens according to the present invention, since the refractive index n4 of the fourth lens satisfies the conditional expression (1),
The total optical length can be shortened, and the radius of curvature R45 of the bonding surface of the bonding lens and the effective focal length f0 of the entire optical system can be configured to satisfy the conditional expression (2). Therefore, the chromatic aberration of magnification can be reduced. Further, since the lower limit is set in the radius of curvature R45 of the joint surface of the joint lens, the central radius of curvature of the lens surface on the image side consisting of the concave curved surface of the fourth lens and the lens surface on the object side consisting of the convex curved surface of the fifth lens large. Therefore, the load on the process is small, for example, the manufacturing process and the joining process of the lens alone can be stably performed. According to this configuration, it is easy to use a material having a high refractive index n4 for the fourth lens, so that it is relatively easy to reduce chromatic aberration of magnification and the like.

In the present invention, when the combined focal length of the fourth lens and the fifth lens is f45, the combined focal length f45 has the following relationship f45 / f0 <3 ... Conditional expression (4).
A mode that satisfies the above conditions can be adopted. According to such a configuration, chromatic aberration and the like can be reduced.

In the present invention, when the focal length of the fourth lens is f4, the focal length f4 has the following relationship: -2 <f4 / f0 <0 ... Conditional expression (5)
A mode that satisfies the above conditions can be adopted.

In the present invention, when the combined focal lengths of the first lens and the second lens are f12, and the combined focal lengths of the third lens, the fourth lens, and the fifth lens are f345, the combined focal lengths f12 and The composite focal length f345 has the following relationship: -1 <f12 / f345 <0 ... Conditional expression (6)
A mode that satisfies the above conditions can be adopted. According to such a configuration, it is possible to reduce overall aberration. Moreover, since f12 / f345 is negative, it is advantageous in terms of temperature characteristics.

In the present invention, an aspect in which the horizontal angle of view is 120 degrees or more can be adopted.

In the wide-angle lens according to the present invention, since the refractive index n4 of the fourth lens satisfies the conditional equation (1), the total optical length can be shortened, the radius of curvature R45 of the joint surface of the joint lens, and the entire optical system. The effective focal length f0 can be configured to satisfy the conditional expression (2). Therefore, the chromatic aberration of magnification can be reduced. Further, since the lower limit is set in the radius of curvature R45 of the joint surface of the joint lens, the central radius of curvature of the lens surface on the image side formed by the concave curved surface of the fourth lens and the lens surface on the object side formed by the convex curved surface of the fifth lens large. Therefore, the load on the process is small, for example, the manufacturing process and the joining process of the lens alone can be stably performed.

It is explanatory drawing of the wide-angle lens which concerns on the reference example of this invention. It is explanatory drawing which shows each lens data, aspherical surface coefficient and the like in the wide-angle lens shown in FIG. It is explanatory drawing which shows the astigmatism of the wide-angle lens shown in FIG. It is explanatory drawing which shows the lateral aberration of the wide-angle lens shown in FIG. It is explanatory drawing of the wide-angle lens which concerns on Example 1 of this invention. It is explanatory drawing which shows each lens data, aspherical surface coefficient and the like in the wide-angle lens shown in FIG. It is explanatory drawing which shows the astigmatism of the wide-angle lens shown in FIG. It is explanatory drawing which shows the lateral aberration of the wide-angle lens shown in FIG. It is explanatory drawing of the wide-angle lens which concerns on Example 2 of this invention. It is explanatory drawing which shows each lens data, aspherical surface coefficient and the like in the wide-angle lens shown in FIG. It is explanatory drawing which shows the astigmatism of the wide-angle lens shown in FIG. It is explanatory drawing which shows the lateral aberration of the wide-angle lens shown in FIG. It is explanatory drawing of the wide-angle lens which concerns on Example 3 of this invention. It is explanatory drawing which shows each lens data, aspherical surface coefficient and the like in the wide-angle lens shown in FIG. It is explanatory drawing which shows the astigmatism of the wide-angle lens shown in FIG. It is explanatory drawing which shows the lateral aberration of the wide-angle lens shown in FIG. It is explanatory drawing of the wide-angle lens which concerns on Example 4 of this invention. It is explanatory drawing which shows each lens data, aspherical surface coefficient and the like in the wide-angle lens shown in FIG. It is explanatory drawing which shows the astigmatism of the wide-angle lens shown in FIG. It is explanatory drawing which shows the lateral aberration of the wide-angle lens shown in FIG.

A wide-angle lens to which the present invention is applied will be described with reference to the drawings. In the following description, the unit is mm unless otherwise specified.

[ Reference example ]
FIG. 1 is an explanatory view of a wide-angle lens 10 according to a reference example of the present invention, and FIG. 1 shows surface numbers corresponding to lens data and aspherical coefficients in parentheses. The surface with "*" after the surface number is an aspherical surface. FIG. 2 is an explanatory diagram showing each lens data, aspherical coefficient, and the like in the wide-angle lens 10 shown in FIG. FIG. 3 is an explanatory diagram showing astigmatism of the wide-angle lens 10 shown in FIG. 1, and FIGS. 3A, 3B, and 3C are astigmatism / distortion (distortion) and spherical aberration. , And an explanatory diagram showing chromatic aberration of magnification. In FIG. 3, S is attached to the characteristic in the sagittal direction, and T is attached to the characteristic in the tangier direction. Further, the distortion indicates the rate of change of the image in the central portion and the peripheral portion of the image pickup, and the smaller the absolute value of the numerical value representing the distortion, the higher the accuracy of the lens. FIG. 4 is an explanatory view showing the lateral aberration of the wide-angle lens 10 shown in FIG. 1, and FIGS. 4 (a), (b), (c), and (d) show 0 deg, 29.46 deg, and 55.40 deg. , 76.76 deg, 95.90 deg, and lateral aberrations in the X-axis direction and the Y-axis direction are shown. In FIGS. 3 and 4, (R) is attached to the aberration for light of wavelength 645, (G) is attached to the aberration for light of wavelength 588, and (B) is attached to the aberration for light of wavelength 486. Is attached. The aspherical coefficients A4, A6, A8, and A10 shown in FIG. 2 correspond to the respective coefficients in the following aspherical functions. Here, Z is the sag amount, c is the reciprocal of the radius of curvature, K is the conical coefficient, and r is the ray height.

The wide-angle lens 10 shown in FIG. 1 has a horizontal angle of view of 120 degrees or more. In the wide-angle lens 10, the first lens 11, the second lens 12, the third lens 13, the diaphragm 17, the fourth lens 14, and the fifth lens 15 are arranged in this order from the object side to the image side, and the fifth lens 15 The filter 18 and the image pickup element 19 are arranged in order on the image side with respect to the lens 15. The first lens 11 is a negative meniscus lens with a convex surface facing the object side. In the present embodiment, the object-side surface (first surface 1) formed of the convex surface of the first lens 11 is a spherical surface, and the image-side surface (second surface 2) formed of the concave surface is an aspherical surface.

The second lens 12 is a negative lens with a concave surface facing the image side. In the present embodiment, the second lens 12 is a negative meniscus lens having a concave surface facing the image side, and is a lens surface on the object side (third surface 3) composed of a convex surface and a lens surface (third surface 3) on the image side composed of a concave surface. At least one of the four surfaces 4) is aspherical. In this embodiment, both the object-side surface (third surface 3) and the image-side surface (fourth surface 4) of the second lens 12 are aspherical surfaces.

The third lens 13 is a positive meniscus lens or a biconvex lens having a convex surface facing the image side, and is at least one of a lens surface (fifth surface 5) on the object side and a lens surface (sixth surface 6) on the image side. Is an aspherical surface. In the present embodiment, the third lens 13 is a biconvex lens, and both the object-side surface (fifth surface 5) composed of convex surfaces and the image-side surface (sixth surface 6) composed of convex surfaces are aspherical surfaces. is there.

The fourth lens 14 is a negative meniscus lens or a biconcave lens with a concave surface facing the image side. In the present embodiment, the fourth lens 14 is a negative meniscus lens having a concave surface facing the image side, and is an object-side surface (eighth surface 8) formed of a convex surface of the fourth lens 14 and an image-side surface formed of a concave surface. Both surfaces (9th surface 9) are aspherical.

The fifth lens 15 is a biconvex lens. The fourth lens 14 and the fifth lens 15 are plastic lenses, and constitute a bonded lens 16 in which the lens surface on the image side of the fourth lens 14 and the lens surface on the object side of the fifth lens are joined. Both the bonding surface (9th surface 9) of the bonding lens 16 and the image-side surface (10th surface 10) formed of the convex surface of the 5th lens 15 are aspherical surfaces. In this embodiment, the first lens 11, the second lens 12, and the third lens 13 are also plastic lenses like the fourth lens 14 and the fifth lens.

Table 1 shows the main parameters of the wide-angle lens 10 configured in this way. The parameters shown in Table 1 are as follows. In addition, Table 1 also shows the parameters of Examples 1 to 4 described later.
f0 ... Effective focal distance of the entire lens system f4 ... Focal distance of the 4th lens 14 f12 ... Combined focal distance of the 1st lens 11 and the 2nd lens 12 f345 ... The 3rd lens 13, the 4th lens 14, and Combined focal distance of the 5th lens 15 f45 ... Combined focal distance of the 4th lens 14 and 5th lens 15 R45 ... Center radius of curvature of the junction surface of the junction lens 16 n4 ... Refractive coefficient of the 4th lens ν4.・ Abbe number of the 4th lens 14

As shown in FIG. 2, in the wide-angle lens 10, the effective focal length f0 (Effective Focal Length) of the entire optical system is 0.822 mm, and the distance between objects (Total Track / total optical length) is 9.206 mm. The F value (Image Space F / #) of the entire lens system is 2.4, the maximum angle of view (Max. Field Angle) is 192 deg, and the horizontal angle of view (Horizontal Field Angle) is 192 deg.

Further, as shown in FIG. 2 and Table 1, the wide-angle lens 10 satisfies all of the following conditional expressions (1), (2), (3), (4), (5), and (6). First, the refractive index n4 of the fourth lens 14 is 1.632, which satisfies the following conditional expression (1).
n4 ≧ 1.632・ ・ ・ Conditional expression (1)

Further, the central radius of curvature R45 of the joint surface (9th surface 9) of the joint lens 16 is 0.515 mm, and the effective focal length f0 of the entire lens system is 0.822 mm. Therefore, the following conditional expression (2) is satisfied.
0.5 << R45 / f0 | = 0.627 <0.8 ... Conditional expression (2)

Further, the Abbe number ν4 of the fourth lens 14 is 23.3, which satisfies the following conditional expression (3).
ν4 ≤ 24 ... Conditional expression (3)

As the material used for the fourth lens 14, for example, an optical polyester resin (OKP4HT) manufactured by Osaka Gas Chemical Co., Ltd. can be exemplified.

The combined focal length f45 of the fourth lens 14 and the fifth lens 15 is 2.314 mm, and the effective focal length f0 of the entire lens system is 0.822 mm. Therefore, the following conditional expression (4) is satisfied.
f45 / f0 = 2.816 <3 ... Conditional expression (4)

The focal length f4 of the fourth lens 14 is −1.454 mm, and the effective focal length f0 of the entire lens system is 0.822 mm. Therefore, the focal length f4 satisfies the following conditional expression (5).
-2 <f4 / f0 = -1.769 <0 ... Conditional expression (5)

The combined focal length f12 of the first lens 11 and the second lens 12 is −0.889 mm, and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 is 2.182 mm. Therefore, the composite focal length f12 and the composite focal length f345 satisfy the following conditional expression (6).
-1 <f12 / f345 = -0.408 <0 ... Conditional expression (6)
Meet.

The astigmatism / distortion (distortion), spherical aberration, and chromatic aberration of magnification of the wide-angle lens 10 configured in this way are as shown in FIG. 3, and the lateral aberration is as shown in FIG. small.

(Main effect of this form)
As described above, the wide-angle lens 10 of this embodiment has a lens configuration of 5 elements in 4 groups, and all of the 5 elements are made of plastic lenses. Therefore, the wide-angle lens 10 can be compact, lightweight, and low-cost even if the horizontal angle of view is 120 ° or more. Further, since eight of the nine surfaces are aspherical, aberration can be reduced with a small number of surfaces as shown in FIG.

Further, in the wide-angle lens 10 of the present embodiment, the refractive index n4 of the fourth lens 14 satisfies the conditional expression (1), and the refractive index n4 is larger than 1.6. Therefore, the total optical length of the wide-angle lens 10 can be shortened, and the radius of curvature R45 of the bonding surface (9th surface 9) of the bonding lens 16 and the effective focal length f0 of the entire optical system form the conditional equation (2). Easy to configure to meet. Therefore, the chromatic aberration of magnification can be reduced. Further, since the lower limit is provided for the radius of curvature R45 of the joining surface (9th surface 9) of the joining lens 16, an object formed by the image side lens surface formed by the concave curved surface of the fourth lens 14 and the convex curved surface of the fifth lens 15. The central radius of curvature of the lens surface on the side is large. Therefore, the load on the process is small, for example, the manufacturing process and the joining process of the lens alone can be stably performed. Moreover, the Abbe number ν4 of the fourth lens 14 satisfies the conditional expression (3), and the Abbe number ν4 is smaller than 27. Therefore, since it is easy to use a material having a high refractive index n4 for the fourth lens 14, it is possible to reduce chromatic aberration of magnification and the like.

Further, the combined focal length f45 of the fourth lens 14 and the fifth lens 15 is short, and the conditional expression (4) is satisfied. Therefore, chromatic aberration and the like can be reduced. Further, the focal length f4 of the fourth lens 14 is short, and the conditional expression (5) is satisfied. Therefore, it is advantageous for reducing chromatic aberration. Further, the combined focal length f12 of the first lens 11 and the second lens 12 and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 satisfy the conditional expression (6), and the first lens 1 The polarity of the combined focal length f12 of the lens 11 and the second lens 12 is negative. Therefore, it is advantageous in terms of temperature characteristics.

[Example 1 ]
FIG. 5 is an explanatory view of the wide-angle lens 10 according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram showing each lens data, aspherical coefficient, and the like in the wide-angle lens 10 shown in FIG. FIG. 7 is an explanatory diagram showing the aberration of the wide-angle lens 10 shown in FIG. FIG. 8 is an explanatory diagram showing the lateral aberration of the wide-angle lens 10 shown in FIG. Since the basic configuration of this embodiment is the same as that of the reference example , the common parts are illustrated with the same reference numerals, and detailed description thereof will be omitted.

Similar to the reference example , the wide-angle lens 10 shown in FIG. 5 has a horizontal angle of view of 120 degrees or more, and has a first lens 11, a second lens 12, a third lens 13, and an aperture 17 from the object side to the image side. The fourth lens 14 and the fifth lens 15 are arranged in this order. The first lens 11 is a negative meniscus lens with a convex surface facing the object side. In the present embodiment, the object-side surface (first surface 1) formed of the convex surface of the first lens 11 is a spherical surface, and the image-side surface (second surface 2) formed of the concave surface is an aspherical surface.

The second lens 12 is a negative lens with a concave surface facing the image side. In the present embodiment, the second lens 12 is a negative meniscus lens having a concave surface facing the image side, and is a lens surface on the object side (third surface 3) composed of a convex surface and a lens surface (third surface 3) on the image side composed of a concave surface. At least one of the four surfaces 4) is aspherical. In this embodiment, both the object-side surface (third surface 3) and the image-side surface (fourth surface 4) of the second lens 12 are aspherical surfaces.

The third lens 13 is a positive meniscus lens or a biconvex lens having a convex surface facing the image side, and is at least one of a lens surface (fifth surface 5) on the object side and a lens surface (sixth surface 6) on the image side. Is an aspherical surface. In the present embodiment, the third lens 13 is a positive meniscus lens having a convex surface facing the image side, and is a concave surface on the object side (fifth surface 5) and a convex surface on the image side (sixth surface). Both of 6) are aspherical.

The fourth lens 14 is a negative meniscus lens or a biconcave lens with a concave surface facing the image side. In the present embodiment, the fourth lens 14 is a negative meniscus lens having a concave surface facing the image side, and is an object-side surface (eighth surface 8) formed of a convex surface of the fourth lens 14 and an image-side surface formed of a concave surface. Both surfaces (9th surface 9) are aspherical.

The fifth lens 15 is a biconvex lens. The fourth lens 14 and the fifth lens 15 are plastic lenses, and constitute a bonded lens 16 in which the lens surface on the image side of the fourth lens 14 and the lens surface on the object side of the fifth lens are joined. Both the bonding surface (9th surface 9) of the bonding lens 16 and the image-side surface (10th surface 10) formed of the convex surface of the 5th lens 15 are aspherical surfaces. In this embodiment, the first lens 11, the second lens 12, and the third lens 13 are also plastic lenses like the fourth lens 14 and the fifth lens.

In the wide-angle lens 10 configured in this way, the effective focal length f0 of the entire optical system is 1.410 mm, the distance between objects is 11.378 mm, and the F value of the entire lens system is 2.0, which is the maximum. The angle of view is 156 deg and the horizontal angle of view is 130 deg.

Further, as shown in FIG. 6 and Table 1, the wide-angle lens 10 satisfies all of the following conditional expressions (1), (2), (3), (4), (5), and (6). First, the refractive index n4 of the fourth lens 14 is 1.632, which satisfies the conditional expression (1). The central radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 is 0.750 mm, and the effective focal length f0 of the entire lens system is 1.410. Therefore, | R45 / f0 | is 0.532, which satisfies the conditional expression (2). The Abbe number ν4 of the fourth lens 14 is 23.3, which satisfies the conditional expression (3).

Since the combined focal length f45 of the fourth lens 14 and the fifth lens 15 is 3.057 mm and the effective focal length f0 of the entire lens system is 1.410 mm, f45 / f0 is 2.168, and the conditional expression ( 4) is satisfied. Since the focal length f4 of the fourth lens 14 is -2.787 mm and the effective focal length f0 of the entire lens system is 1.410 mm, f4 / f0 = -1.976, which satisfies the conditional expression (5). ing. The combined focal length f12 of the first lens 11 and the second lens 12 is −1.662 mm, and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 is 2.648 mm. Therefore, f12 / f345 = −0.628, which satisfies the conditional expression (6).

The astigmatism / distortion (distortion), spherical aberration, and chromatic aberration of magnification of the wide-angle lens 10 configured in this way are as shown in FIG. 7, and the lateral aberration is as shown in FIG. small.

As described above, the wide-angle lens 10 of this embodiment has a lens configuration of 5 elements in 4 groups, and all of the 5 elements are made of plastic lenses. Therefore, the wide-angle lens 10 can be compact, lightweight, and low-cost even if the horizontal angle of view is 120 ° or more. Further, since eight of the nine surfaces are aspherical, aberration can be reduced with a small number of surfaces as shown in FIG. 7.

Further, in the wide-angle lens 10 of the present embodiment, the radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 and the effective focal length f0 of the entire optical system satisfy the conditional equation (2), so that chromatic aberration of magnification Can be reduced. Further, since the lower limit is provided for the radius of curvature R45 of the joining surface (9th surface 9) of the joining lens 16, an object formed by the image side lens surface formed by the concave curved surface of the fourth lens 14 and the convex curved surface of the fifth lens 15. The central radius of curvature of the lens surface on the side is large. Therefore, the same effect as that of the reference example can be obtained, such as being able to stably perform the manufacturing process and the joining process of the lens alone.

[Example 2 ]
FIG. 9 is an explanatory view of the wide-angle lens 10 according to the second embodiment of the present invention. FIG. 10 is an explanatory diagram showing each lens data, aspherical coefficient, and the like in the wide-angle lens 10 shown in FIG. FIG. 11 is an explanatory diagram showing the aberration of the wide-angle lens 10 shown in FIG. FIG. 12 is an explanatory diagram showing the lateral aberration of the wide-angle lens 10 shown in FIG. Since the basic configuration of this embodiment is the same as that of the reference example , the common parts are illustrated with the same reference numerals, and detailed description thereof will be omitted.

The wide-angle lens 10 shown in FIG. 9 has a horizontal angle of view of 120 degrees or more, as in the reference example, and has a first lens 11, a second lens 12, a third lens 13, and an aperture 17 from the object side to the image side. The fourth lens 14 and the fifth lens 15 are arranged in this order. The first lens 11 is a negative meniscus lens with a convex surface facing the object side. In this embodiment, both the convex surface of the first lens 11 on the object side (first surface 1) and the concave surface on the image side (second surface 2) are spherical surfaces.

The second lens 12 is a negative lens with a concave surface facing the image side. In the present embodiment, the second lens 12 is a negative meniscus lens having a concave surface facing the image side, and is a lens surface on the object side (third surface 3) composed of a convex surface and a lens surface (third surface 3) on the image side composed of a concave surface. At least one of the four surfaces 4) is aspherical. In this embodiment, both the object-side surface (third surface 3) and the image-side surface (fourth surface 4) of the second lens 12 are aspherical surfaces.

The third lens 13 is a positive meniscus lens or a biconvex lens having a convex surface facing the image side, and is at least one of a lens surface (fifth surface 5) on the object side and a lens surface (sixth surface 6) on the image side. Is an aspherical surface. In the present embodiment, the third lens 13 is a positive meniscus lens having a convex surface facing the image side, and is a concave surface on the object side (fifth surface 5) and a convex surface on the image side (sixth surface). Both of 6) are aspherical.

The fourth lens 14 is a negative meniscus lens or a biconcave lens with a concave surface facing the image side. In the present embodiment, the fourth lens 14 is a negative meniscus lens having a concave surface facing the image side, and is an object-side surface (eighth surface 8) formed of a convex surface of the fourth lens 14 and an image-side surface formed of a concave surface. Both surfaces (9th surface 9) are aspherical.

The fifth lens 15 is a biconvex lens. The fourth lens 14 and the fifth lens 15 are plastic lenses, and constitute a bonded lens 16 in which the lens surface on the image side of the fourth lens 14 and the lens surface on the object side of the fifth lens are joined. Both the bonding surface (9th surface 9) of the bonding lens 16 and the image-side surface (10th surface 10) formed of the convex surface of the 5th lens 15 are aspherical surfaces. In this embodiment, the first lens 11 is a glass lens, and the second lens 12 and the third lens 13 are plastic lenses like the fourth lens 14 and the fifth lens.

In the wide-angle lens 10 configured in this way, the effective focal length f0 of the entire optical system is 1.410 mm, the distance between objects is 11.465 mm, and the F value of the entire lens system is 2.0, which is the maximum. The angle of view is 156 deg and the horizontal angle of view is 131 deg.

Further, as shown in FIG. 10 and Table 1, the wide-angle lens 10 satisfies all of the following conditional expressions (1), (2), (3), (4), (5), and (6). First, the refractive index n4 of the fourth lens 14 is 1.632, which satisfies the conditional expression (1). The central radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 is 0.764 mm, and the effective focal length f0 of the entire lens system is 1.410. Therefore, | R45 / f0 | is 0.542, which satisfies the conditional expression (2). The Abbe number ν4 of the fourth lens 14 is 23.3, which satisfies the conditional expression (3).

Since the combined focal length f45 of the fourth lens 14 and the fifth lens 15 is 3.205 mm and the effective focal length f0 of the entire lens system is 1.410 mm, f45 / f0 is 2.272, and the conditional expression ( 4) is satisfied. Since the focal length f4 of the fourth lens 14 is -2.249 mm and the effective focal length f0 of the entire lens system is 1.410 mm, f4 / f0 = -1.595, which satisfies the conditional expression (5). ing. The combined focal length f12 of the first lens 11 and the second lens 12 is -1.807 mm, and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 is 2.671 mm. Therefore, f12 / f345 = −0.676, which satisfies the conditional expression (6).

The astigmatism / distortion (distortion), spherical aberration, and chromatic aberration of magnification of the wide-angle lens 10 configured in this way are as shown in FIG. 11, and the lateral aberration is as shown in FIG. small.

As described above, the wide-angle lens 10 of this embodiment has a lens configuration of 5 elements in 4 groups, and the 4 elements are made of a plastic lens. Therefore, the wide-angle lens 10 can be compact, lightweight, and low-cost even if the horizontal angle of view is 120 ° or more. Further, since seven of the nine surfaces are aspherical, aberration can be reduced with a small number of surfaces as shown in FIG.

Further, in the wide-angle lens 10 of the present embodiment, the radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 and the effective focal length f0 of the entire optical system satisfy the conditional equation (2), so that chromatic aberration of magnification Can be reduced. Further, since the lower limit is provided for the radius of curvature R45 of the joining surface (9th surface 9) of the joining lens 16, an object formed by the image side lens surface formed by the concave curved surface of the fourth lens 14 and the convex curved surface of the fifth lens 15. The central radius of curvature of the lens surface on the side is large. Therefore, the same effect as that of the reference example can be obtained, such as being able to stably perform the manufacturing process and the joining process of the lens alone.

[Example 3 ]
FIG. 13 is an explanatory view of the wide-angle lens 10 according to the third embodiment of the present invention. FIG. 14 is an explanatory diagram showing each lens data, aspherical coefficient, and the like in the wide-angle lens 10 shown in FIG. FIG. 15 is an explanatory diagram showing the aberration of the wide-angle lens 10 shown in FIG. FIG. 16 is an explanatory diagram showing the lateral aberration of the wide-angle lens 10 shown in FIG. Since the basic configuration of this embodiment is the same as that of the reference example , the common parts are illustrated with the same reference numerals, and detailed description thereof will be omitted.

The wide-angle lens 10 shown in FIG. 13 has a horizontal angle of view of 120 degrees or more, as in the reference example, and has a first lens 11, a second lens 12, a third lens 13, and an aperture 17 from the object side to the image side. The fourth lens 14 and the fifth lens 15 are arranged in this order. The first lens 11 is a negative meniscus lens with a convex surface facing the object side. In this embodiment, both the convex surface of the first lens 11 on the object side (first surface 1) and the concave surface on the image side (second surface 2) are spherical surfaces.

The second lens 12 is a negative lens with a concave surface facing the image side. In the present embodiment, the second lens 12 is a negative meniscus lens having a concave surface facing the image side, and is a lens surface on the object side (third surface 3) composed of a convex surface and a lens surface (third surface 3) on the image side composed of a concave surface. At least one of the four surfaces 4) is aspherical. In this embodiment, both the object-side surface (third surface 3) and the image-side surface (fourth surface 4) of the second lens 12 are aspherical surfaces.

The third lens 13 is a positive meniscus lens or a biconvex lens having a convex surface facing the image side, and is at least one of a lens surface (fifth surface 5) on the object side and a lens surface (sixth surface 6) on the image side. Is an aspherical surface. In the present embodiment, the third lens 13 is a positive meniscus lens having a convex surface facing the image side, and is a concave surface on the object side (fifth surface 5) and a convex surface on the image side (sixth surface). Both of 6) are aspherical.

The fourth lens 14 is a negative meniscus lens or a biconcave lens with a concave surface facing the image side. In the present embodiment, the fourth lens 14 is a negative meniscus lens having a concave surface facing the image side, and is an object-side surface (eighth surface 8) formed of a convex surface of the fourth lens 14 and an image-side surface formed of a concave surface. Both surfaces (9th surface 9) are aspherical.

The fifth lens 15 is a biconvex lens. The fourth lens 14 and the fifth lens 15 are plastic lenses, and constitute a bonded lens 16 in which the lens surface on the image side of the fourth lens 14 and the lens surface on the object side of the fifth lens are joined. Both the bonding surface (9th surface 9) of the bonding lens 16 and the image-side surface (10th surface 10) formed of the convex surface of the 5th lens 15 are aspherical surfaces. In this embodiment, the first lens 11 is a glass lens, and the second lens 12 and the third lens 13 are plastic lenses like the fourth lens 14 and the fifth lens.

In the wide-angle lens 10 configured in this way, the effective focal length f0 of the entire optical system is 1.056 mm, the distance between objects is 11.794 mm, and the F value of the entire lens system is 2.0, which is the maximum. The angle of view is 193 deg, and the horizontal angle of view is 193 deg.

Further, as shown in FIG. 14 and Table 1, the wide-angle lens 10 satisfies all of the following conditional expressions (1), (2), (3), (4), (5), and (6). First, the refractive index n4 of the fourth lens 14 is 1.637, which satisfies the conditional expression (1). Further, the radius of curvature R45 of the central curvature of the bonding surface (9th surface 9) of the bonding lens 16 is 0.615 mm, and the effective focal length f0 of the entire lens system is 1.056. Therefore, | R45 / f0 | is 0.582, which satisfies the conditional expression (2). The Abbe number ν4 of the fourth lens 14 is 24.0, which satisfies the conditional expression (3).

Since the combined focal length f45 of the fourth lens 14 and the fifth lens 15 is 3.055 mm and the effective focal length f0 of the entire lens system is 1.056 mm, f45 / f0 is 2.894, and the conditional expression ( 4) is satisfied. Since the focal length f4 of the fourth lens 14 is −1.528 mm and the effective focal length f0 of the entire lens system is 1.056 mm, f4 / f0 = −1.447, which satisfies the conditional expression (5). ing. The combined focal length f12 of the first lens 11 and the second lens 12 is -1.71 mm, and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 is 2.088 mm. Therefore, f12
/ F345 = −0.819, which satisfies the conditional expression (6).

The astigmatism / distortion (distortion), spherical aberration, and chromatic aberration of magnification of the wide-angle lens 10 configured in this way are as shown in FIG. 15, and the lateral aberration is as shown in FIG. small.

As described above, the wide-angle lens 10 of this embodiment has a lens configuration of 5 elements in 4 groups, and the 4 elements are made of a plastic lens. Therefore, the wide-angle lens 10 can be compact, lightweight, and low-cost even if the horizontal angle of view is 120 ° or more. Further, since seven of the nine surfaces are aspherical, aberration can be reduced with a small number of surfaces as shown in FIG.

Further, in the wide-angle lens 10 of the present embodiment, the radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 and the effective focal length f0 of the entire optical system satisfy the conditional equation (2), so that chromatic aberration of magnification Can be reduced. Further, since the lower limit is provided for the radius of curvature R45 of the joining surface (9th surface 9) of the joining lens 16, an object formed by the image side lens surface formed by the concave curved surface of the fourth lens 14 and the convex curved surface of the fifth lens 15. The central radius of curvature of the lens surface on the side is large. Therefore, the same effect as that of the reference example can be obtained, such as being able to stably perform the manufacturing process and the joining process of the lens alone.

[Example 4 ]
FIG. 17 is an explanatory view of the wide-angle lens 10 according to the fourth embodiment of the present invention. FIG. 18 is an explanatory diagram showing each lens data, aspherical coefficient, and the like in the wide-angle lens 10 shown in FIG. FIG. 19 is an explanatory diagram showing the aberration of the wide-angle lens 10 shown in FIG. FIG. 20 is an explanatory diagram showing the lateral aberration of the wide-angle lens 10 shown in FIG. Since the basic configuration of this embodiment is the same as that of the reference example , the common parts are illustrated with the same reference numerals, and detailed description thereof will be omitted.

The wide-angle lens 10 shown in FIG. 17 has a horizontal angle of view of 120 degrees or more, as in the reference example, and has a first lens 11, a second lens 12, a third lens 13, and an aperture 17 from the object side to the image side. The fourth lens 14 and the fifth lens 15 are arranged in this order. The first lens 11 is a negative meniscus lens with a convex surface facing the object side. In this embodiment, both the convex surface of the first lens 11 on the object side (first surface 1) and the concave surface on the image side (second surface 2) are spherical surfaces.

The second lens 12 is a negative lens with a concave surface facing the image side. In the present embodiment, the second lens 12 is a biconcave lens, and at least one of a concave lens surface on the object side (third surface 3) and a concave lens surface on the image side (fourth surface 4) is It is an aspherical surface. In this embodiment, both the object-side surface (third surface 3) and the image-side surface (fourth surface 4) of the second lens 12 are aspherical surfaces.

The third lens 13 is a positive meniscus lens or a biconvex lens having a convex surface facing the image side, and is at least one of a lens surface (fifth surface 5) on the object side and a lens surface (sixth surface 6) on the image side. Is an aspherical surface. In the present embodiment, the third lens 13 is a positive meniscus lens having a convex surface facing the image side, and is a concave surface on the object side (fifth surface 5) and a convex surface on the image side (sixth surface). Both of 6) are aspherical.

The fourth lens 14 is a negative meniscus lens or a biconcave lens with a concave surface facing the image side. In the present embodiment, the fourth lens 14 is a negative meniscus lens having a concave surface facing the image side, and is an object-side surface (eighth surface 8) formed of a convex surface of the fourth lens 14 and an image-side surface formed of a concave surface. Both surfaces (9th surface 9) are aspherical.

The fifth lens 15 is a biconvex lens. The fourth lens 14 and the fifth lens 15 are plastic lenses, and constitute a bonded lens 16 in which the lens surface on the image side of the fourth lens 14 and the lens surface on the object side of the fifth lens are joined. Both the bonding surface (9th surface 9) of the bonding lens 16 and the image-side surface (10th surface 10) formed of the convex surface of the 5th lens 15 are aspherical surfaces.

In this embodiment, the first lens 11 is a glass lens, and the second lens 12 and the third lens 13 are plastic lenses like the fourth lens 14 and the fifth lens.
In the wide-angle lens 10 configured in this way, the effective focal length f0 of the entire optical system is 0.669 mm, the distance between objects is 11.702 mm, and the F value of the entire lens system is 2.0, which is the maximum. The angle of view is 196 deg and the horizontal angle of view is 161 deg.

Further, as shown in FIG. 18 and Table 1, the wide-angle lens 10 satisfies all of the following conditional expressions (1), (2), (3), (4), (5), and (6). First, the refractive index n4 of the fourth lens 14 is 1.637, which satisfies the conditional expression (1). Further, the central radius of curvature R45 of the joint surface (9th surface 9) of the joint lens 16 is 0.472 mm, and the effective focal length f0 of the entire lens system is 0.669. Therefore, | R45 / f0 | is 0.705, which satisfies the conditional expression (2). The Abbe number ν4 of the fourth lens 14 is 24.0, which satisfies the conditional expression (3).

Since the combined focal length f45 of the fourth lens 14 and the fifth lens 15 is 1.884 mm and the effective focal length f0 of the entire lens system is 0.669 mm, f45 / f0 is 2.815, and the conditional expression ( 4) is satisfied. Since the focal length f4 of the fourth lens 14 is −1.062 mm and the effective focal length f0 of the entire lens system is 0.669 mm, f4 / f0 = −1.587, which satisfies the conditional expression (5). ing. The combined focal length f12 of the first lens 11 and the second lens 12 is −1.428 mm, and the combined focal length f345 of the third lens 13, the fourth lens 14 and the fifth lens 15 is 2.372 mm. Therefore, f12 / f345 = −0.602, which satisfies the conditional expression (6).

The astigmatism / distortion (distortion), spherical aberration, and chromatic aberration of magnification of the wide-angle lens 10 configured in this way are as shown in FIG. 19, and the lateral aberration is as shown in FIG. small.

As described above, the wide-angle lens 10 of this embodiment has a lens configuration of 5 elements in 4 groups, and the 4 elements are made of a plastic lens. Therefore, the wide-angle lens 10 can be compact, lightweight, and low-cost even if the horizontal angle of view is 120 ° or more. Further, since seven of the nine surfaces are aspherical, aberration can be reduced with a small number of surfaces as shown in FIG.

Further, in the wide-angle lens 10 of the present embodiment, the radius of curvature R45 of the junction surface (9th surface 9) of the junction lens 16 and the effective focal length f0 of the entire optical system satisfy the conditional equation (2), so that chromatic aberration of magnification Can be reduced. Further, since the lower limit is provided for the radius of curvature R45 of the joining surface (9th surface 9) of the joining lens 16, an object formed by the image side lens surface formed by the concave curved surface of the fourth lens 14 and the convex curved surface of the fifth lens 15. The central radius of curvature of the lens surface on the side is large. Therefore, the same effect as that of the reference example can be obtained, such as being able to stably perform the manufacturing process and the joining process of the lens alone.

10 ... wide-angle lens, 11 ... 1st lens, 12 ... 2nd lens, 13 ... 3rd lens, 14 ... 4th lens, 15 ... 5th lens, 16 ... junction lens, 17 ... aperture, 18 ... filter, 19 ... Image sensor

Claims (5)

It consists of a first lens, a second lens, a third lens, an aperture, a fourth lens, and a fifth lens arranged in order from the object side to the image side.
The first lens is a negative meniscus lens with a convex surface facing the object side and a concave surface facing the image side.
The second lens is a negative lens having a concave surface facing the image side, and at least one of the lens surface on the object side and the lens surface on the image side is an aspherical surface.
The third lens is a positive meniscus lens having a concave surface facing the object side and a convex surface facing the image side, and at least one of the lens surface on the object side and the lens surface on the image side is an aspherical surface.
The fourth lens is a negative meniscus lens with a concave surface facing the image side, or a biconcave lens.
The fifth lens is a biconvex lens.
The fourth lens and the fifth lens are plastic lenses, and constitute a bonded lens in which the lens surface on the image side of the fourth lens and the lens surface on the object side of the fifth lens are joined.
When the refractive index of the fourth lens is n4, the refractive index n4 has the following relationship.
n4 ≧ 1.632
The filling,
When the radius of curvature of the center of the junction surface of the junction lens is R45 and the effective focal length of the entire lens system is f0, the radius of curvature R45 and the effective focal length f0 have the following relationship.
0.5 << R45 / f0 | <0.8
The filling,
When the Abbe number of the fourth lens is ν4, the Abbe number ν4 has the following relationship.
ν4 ≦ 24
A wide-angle lens characterized by satisfying. When the combined focal lengths of the fourth lens and the fifth lens are f45, the combined focal lengths f45 have the following relationship f45 / f0 <3.
The wide-angle lens according to claim 1, wherein the wide-angle lens satisfies the above. When the focal length of the fourth lens is f4, the focal length f4 has the following relationship -2 <f4 / f0 <0.
The wide-angle lens according to claim 1 or 2 , wherein the wide-angle lens satisfies the above. When the combined focal length of the first lens and the second lens is f12 and the combined focal length of the third lens, the fourth lens and the fifth lens is f345, the combined focal length f12 and the combined focal length f345 Is the following relationship -1 <f12 / f345 <0
The wide-angle lens according to any one of claims 1 to 3 , wherein the wide-angle lens satisfies. The wide-angle lens according to any one of claims 1 to 4 , wherein the horizontal angle of view is 120 degrees or more.

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